1. Field of the Invention
The present invention relates to a TV program search apparatus that allows users to search for TV programs on the basis of a user's preferences.
2. Description of the Related Art
In recent years, functions to make TV watching and the recording of TV programs easier have been developed as a result of the digitization of TV systems.
Of those functions, in a TV recorder using a high-capacity storage such as a HD (Hard Disk), timer recording can be easily accomplished by combining the high capacity storage with an EPG (Electronic Program Guide), causing a substantial change to the TV watching styles of users.
Additionally, functions which automatically record programs containing keywords that a user is interested in and which recommend programs that match a user's preferences by automatically determining the preferences on the basis of the user's recording history have been developed.
In the function for recommending a program reflecting a user's preferences, a crucial point is the degree of similarity (accuracy) between a user's preferences and the programs recommended.
A technique for deriving a user's preferences on the basis of recording history discovers the recording history of TV programs (recorded programs and programs preferred by a user), obtains the contents of the recorded programs from the text information of the EPG, and extracts the common grounds in the recorded programs on the basis of the EPG contents.
Finally, programs with contents similar to the above common grounds (preference information) are selected from the programs to be broadcast in the future. This is the typical method.
As an example of a technique relating to the search for programs on the basis of a user's preferences, an automatic learning recorder for automatically recording a program without timer recording when a user does not watch or record a preferred program has been suggested (see Japanese Patent Application Publication No. 05-062283).
As an example of the use of the degree of similarity between preferences and a program, a television program search apparatus that determines the degree of similarity among combinations of programs by examining the users' program viewing history independently of the frequency of watching has been suggested (see Japanese Patent Application Publication No. 2005-191816).
In addition, a television program search apparatus that calculates the weight of a preference by multiplying the frequency of appearance of a particular keyword with the number of programs that include the keyword has been also suggested (Japanese Patent Application Publication No. 2005-191817).
Furthermore, a broadcasting terminal apparatus having a broadcasting terminal installed with a function for determining programs suitable for a user on the basis of user history and which automatically records the programs suitable for the user without the user proactively initiating this operation has been suggested (Japanese Patent Application Publication No. 2001-86420).
All of the techniques shown in the above patent documents of Japanese Patent Application Publication No. 05-062283, No. 2005-191816, No. 2005-191817, and No. 2001-86420 can automatically extract a user's preferences and search for a recommended program. However, each assumes that a user's preferences are constant and do not change with time.
In other words, the techniques disclosed in the above patent documents lack a technical idea for automatically searching for recommended programs by automatically following changes in a user's preferences when a user's preferences change.
Therefore, the disclosed techniques do not immediately generate search requests reflecting the changed preferences when a user's preferences change.
Consequently, because the recommended programs do not correspond to the change in a user's preferences, the recommended result is far from the user's preferences. This results in a decline in the accuracy of the program search.
All of the methods in the above patent documents have the problem that if a user's preferences change, either the user has to reset the history of the preference information in order to have the program search apparatuses recommend programs on the basis of the changed preferences or the user has to once again accumulate information relating to the user's viewing history in order to reflect these changed preferences.
In a case in which the preference information is not reset, the information relating to the changed preferences (e.g., a word) will appear infrequently at the time of the change, and therefore will not be extracted as preference information.
Consequently, because the recommended results are far from the user's preferences, there is a substantial decline in the accuracy of the program search.
The “Program recommendation functions” was originally designed to automatically find programs that users prefer. Thus, a highly accurate program recommendation function that follows the changes in a user's preferences without any need for the user to reset the operation history at the time the preferences are changed has been sought.
Generally, changes in preferences do not occur suddenly at full scale or in a comprehensive manner. Rather the changes occur gradually without the user realizing that any change has occurred.
Therefore, it is impractical to expect users to reset the operation history at the time of changes in their viewing preferences.